The use of photovoltaic panels on a roof for providing a roof covering is well established.
In previously described systems (such as those outlined in UK patent publication number GB 2,430,943 B), there are described components and systems for connecting a solar panel (also termed herein as a photovoltaic panel) to a roofing structure. In particular, it is described to provide a watertight seal between a solar panel and the traditional roofing structure (e.g. between a solar panel and a conventional roof tile).
In one existing roofing system, solar modules are manufactured with a size and format equivalent to the tiles that they are replacing in the roof. The term solar module is used herein to mean an apparatus including a solar panel and any attachment means affixed therewith. In such roofing structures, the bottom of one row of tiles overlaps the top of a preceding row to ensure that water flows down the roof from the upper row of tiles to the lower. Typically, such a solar module is the size of a row of four adjacent roofing tiles. The solar module may interface with traditional tiles at the boundary directly or there may be a pressed metal flashing kit required to form the boundary between the two materials. This type of roofing system normally suffers from high cost due to the low volume of manufacture compared to standard photovoltaic panels and is labour intensive to install due to the numerous fixings and connections required.
In a second existing roofing system, there is provided a thin waterproof sub-layer below the solar panels. This thin waterproof sub-layer may formed from a roll of corrugated metal or polymer or from a number of overlapping polymer trays. The thin waterproof sub-layer is fixed to the roof by screwing “fixing points” through the sub-layer to the roof below. Standard solar modules are in turn fixed to these fixing points. This embodiment benefits from the economies of scale of utilising standard sized solar modules but suffers from being labour intensive to install, with the resulting quality being highly dependent on the skill and diligence of the installer.